1. (Technical field)
The present invention relates to a magnetic recording medium and a process for producing the same.
2. (Prior art)
Heretofore, magnetic recording media such as magnetic tapes and the like have been produced by mixing and dispersing ferromagnetic powders such as acicular or other particulate magnetic iron oxides with additives such as a dispersing agent, a lubricant, an wear-resistant abrasive and the like, a resinous binder and a solvent in a ball mill, applying the resulting mixture on a support such as polyester film, drying and slitting it into a tape.
Recently, with the increased demand to high density magnetic recording media, efforts have been directed to the improvement in the S/N ratio as well as in the dispersibility of ferromagnetic powder and other additives. However, all of them failed to provide a magnetic recording medium having satisfactory properties. Particularly, it is known in the art that in order to improve the S/N ratio it is required to use fine particle magnetic powder. However, it is not easy to produce a fine particle magnetic powder having superior properties.
The inventor has made an extensive study on acicular magnetic powders having various average particle sizes and found that the shapes of magnetic particles have deviation due to the difficulties in precise control of the manufacturing process, which leads to a poor dispersion of the powder in a resinous binder, resulting in an insufficient increase of the S/N ratio.